Collapsible taper-thread-cutting tool



I 1,622,097 March 22, 1927- R, EDWARDS COLLAPSIBLE TAPER THREAD CUTTING TOOL Filed Jan. 12. .1920 v 2 Sheets-Sheet 1 A' ITORNEY March 7' c, R. EDWARDS Filed Jan. 12. 1920 2 Sheets-Sheet 2 Patented Mar. 22, f927.

UNITED STATS CHARLES R. EDWARDS, OF HOU$TON, TEXAS.

COLLAPSIBLE TAPEB-THREAD-CUTTING TOOL.

Application filed January 12, 1920. serial No. 350,867.

This invention relates to new and useful improvements in a collapsible tapering tap.

One object of the invention is to provide adevice of the character described, which has been specially designed for the purpose of cutting tapered threads, and which may be driven with much less power than is required to drive taps now in common use.

Another object of the invention is to provide a device of the character described by means of which either external or internal threads may be cut, and the particular object sought to be obtained is to provide a collapsible tap whereby a tapering box may be internally threaded and a correspondingly tapered pin may be externally threaded, said pin being designed to be screwed on to said box.

A further object of the invention is to provide a tap of the character described which may be readily collapsed and released from the work, when the thread has been completed so that the tap may be readily withdrawn without injury to it or to the threads.

A further feature of the invention resides in the provision of a device of the character described which is simple in construction and operation and by means of which the work to be done may be quickly accomplished.

l/Vith the above and other objects in view the invention has particular relation to certain novel features of construction, operation, and arrangementof parts, an example of which is given in this specification and illustrated in the accompanying drawings wherein Figure 1 is a side View of the form of tap used for cutting external threads, shown partially in section. V

Figure 2 is an end view thereof,

Figure 3 is a transverse sectional view taken on the line 3, 3 of Figure 1.

Figure 4 is a side view of the chaser carrier,

Figure 5 is an end View thereof,

Figure 6 shows a side elevation, partially in section of the form of tap used for internal threading.

Figure 7 is an end view thereof.

Figures 8 and 9 show plan and side views, respectively, of the chaser carrier employed in this form of tap, and

Figure 10 is an end view thereof.

Referring now more particularly to the drawings wherein like numerals of reference designate similar parts in each of the figures, the numeral 1 refers to the chaser support which in this instance is a die block, into the outer end of which one end of the shank 2 is threaded and the other end of said block 18 formed with an outwardly tapering socket 3 provided to receive the tapering pin 4 whlch 1t is proposed to externally thread. The outer end of the shank 2 carries the holder 5, for connection to the lathe turret or drill press and slidably mounted upon the shank 2 there is a guide 6 disc like in form. The side of this guide facing the die block has the radiating dove-tailed grooves 7 therein into which the outer ends of the chaser carriers 8 are fitted, said carriers being slidable in said grooves and the grooves are inclined, relative to the axis of the shank, so that the carriers 8 will diverge. These carriers arefitted through the corresponding bearings 9 of the block 1 so that when the guide 6 is moved toward the die block the carriers will be forced apart and when said guide is moved from. said block, the carriers will move toward each other. The inner wall of the die block 1 has the radiating grooves 10 which form bearings for the chasers 11. These chasers are fastened to the respective carriers 8 and are blade like in form and their inner edges are serrated forming cutting teeth which are given the required angle for cutting the desired form of threads.

When it is desired to thread the pin 4, the guide 6 is moved back from the block 1 the required distance and the blank pin to be threaded is then started between the chasers 11 and held stationary or rotated while the device is rotated or held stationary by a lathe turret or drill press or other suitable means. The die will feed itself and will cut the threads as it is rotated. When the pin is completely threaded the block 1 is moved toward the guide 6, the shank 2 sliding through said guide, thus causing the chaser carriers and the chasers carried thereby, to move apart thus releasing them from the threads and the die may then be readily withdrawn from the work.

In the form shown in Figures 6 to 10 inclusive, the numeral 12 designates a die chaser support which in this instance is a block which is fixed to the shaft 13 and slidably mounted upon this shaft there is the carrier guide 14: having the radiating dovetailed grooves 15 out in the side thereof facing the tap block. The chaser carriers 16 have one end dovetailed into said grooves and these carriers work through corresponding bearings 17 in the die block 12 and their other ends carry the bladelike chasers 18, whose operative edges are serrated to form internal threads in the tapering box 19.

In operation the guide 14 is adjusted on the shaft 13 to the required position to begin the work and the tap is then rotated through a drill press or other, suitable means.

The chasers take hold of the material of the box 19 and gradually t'eed themselves in, cutting the threads as the carriers are rotated until the stop 20 carried by the block 12 strikes against the end of the box at which point the block 12 is held axially stationary and the threads already cut lead the chasers, together with the chaser carriers, and carrier guide, farther into the box 19 until the required length of thread is cutwhen the stem 13 and block 12 are wit drawn thus closing the chasers until the threads are cleared when the entire tap is withdrawn without backing out or injury to the threads or chasers.

\Vhat I claim is:

1. A device of the character describedineluding a shank, a carrier guide slidable on the shank, and having bearings inclined relative to its axis, a die block fixed to the shank and provided with bearings, carriers slidably connected to said block and working in said bearings of the guide and block andchase'rs carried by said carriers,

2. A device substantially as described, including thread chasers adapted to move so as to describe the surface of frustratedcone, carriers to which said chasers are attached, a carrier guide, said carriers having a slidable connection with the guide, a die block, a shank connected to the block and movable relative to the guide, inclined hearings in said guide and block tlu'ough which said can riers work.

,3. A collapsible taper cutting device including a guide, chasers, means supporting the chasers, a shank movable relative to the guide, a die block fixed to said shank, said guide and block having bearings for said supporting nieans which are inclined, relative to the axis of the guide, corresponding to the inclination of the taper of the work.

4. A collapsible taper cutting device including achaser guide stationary with respect to axial movement relative to the work, a guide support movable relative to the guide, a member connected to said support and formed with bearings inclined relative to the axis of the guide, chaser carriers operatively connected with the guide and Working through said bearings, chasers carried by the carriers and actuated radially by said guide and hearings to describe the surface of frustrated cone, in application to the work,

5. A collapsible taper cutting device including chasers adapted to form the work into frusto-conical contour, a guide, a member movable axially with respect to the guide and having bearings inclined relative to the axis of the guide and means connected to the guide and chasers and working through said bearings and adapted to move the chasers radially during the application to the Work.

6. A collapsible cutting device including a chaser guide, stationary with respect to axial movement relative to the work, chaser carriers, chasers connected to said carriers and operatively connected with the guide, a bearing member having bearings inclined relative to the axis of the guide through which the carriers work and adapted to move the chasers radially, as the chasers advance axially along said work.

7. A collapsible taper cutting device in cluding a guide having bearings, chasers, a bearing member having bearings, chaser carriers Working in the bearings of said guide and member, said bearings and carriers forming operative connections between the chasers and guide adapted to hold the chasers against the tapered. work being cut, all of said bearings being inclined with respect to the axis of the guide and thus formed to operate through the carriers, to release the chasers from the work by the movement of the guide axially toward the work.

8. A device of the character described including a shank, a carrier guide movable lengthwise relative to the shank and having bearings inclined relative to its axis, a meniber connected to the shank and provided with diverging bearings, carriers working through said bearings of said member and also working in said bearings of said guide and chasers carried by said carriers.

In testimony whereof I have signed my name to this specification.

CHARLES R. EDWARDS. 

